Thermite is a ‘pyrotechnic composition’ of metal powder, fuel and metal oxide. When ignited by heat to around 4000F, thermite undergoes an exothermic reduction-oxidation reaction whereby the aluminum (or other reactive powder) reacts with the O3 part of the rust to produce molten iron. It is almost impossible to extinguish.
Mix 76.3% iron oxide with 27.3% aluminum powder to make thermite. The reaction, also called the Goldschmidt process, is used for thermite welding, often used to join rail tracks because the iron seeps into the cracks to make it seamless.
Military around the world use thermite when destruction is required without noise. Because of its high burn temperature, thermite is used to destroy vehicles, cryptographic equipment and artillery, where a thermite grenade is dropped in a cannon barrel to fuse it shut. Military grade thermite adds barium nitrate, sulfur and dextrin. Watch this video to see how much impact a drone delivering thermite to an ammunition dump had in Ukraine.
And if you like watching Big Fires, check out the Mythbusters’ video below.